This research proposal aims to investigate certain specific aspects of growth at a cellular level. We plan to extend our studies of DNA polymerase activity during nomal and altered growth. The phenomena accompanying "catch-up" growth after nutritional rehabilitation are to be characterized in regard to net changes in DNA, RNA, protein and fat and in the temporal patterns of DNA polymerase, thymidine uptake and thymidine kinase. The effects of nutritional alterations on adipose tissue DNA polymerase activity are to be assessed after the normal ontogeny has been described for this enzyme. The ultimate goal is to gain additional information about the mechanisms which control growth which can be eventually applied clinically to disordered growth in children.